Pluto’s Largest Moon Charon is a Gravity Bully

The orbits of Pluto’s four smaller moons are thrown out of kilter by the gravitational tug-of-war between Pluto and its largest moon Charon, a new study shows.

The study, published in the journal Nature, provides new insights into how this chaotic system at the solar system’s outer rim formed.

Unlike most planetary systems which consist of a planet orbited by moons, Pluto and its largest moon Charon orbit each other around a common centre of gravity in a binary system.

This in turn is orbited by four smaller moons — Nix, Hydra, Kerebos and Styx.

“We’ve learnt that it’s not easy orbiting a binary planetary system, it’s weird, because these small moons aren’t orbiting a single object, they’re orbiting two objects Pluto and Charon,” says the study’s lead author Dr Mark Showalter of the SETI Institute.

“These objects were just tumbling wildly and that was our first clue that there was something very weird about the Pluto system.”